When you associate one or more customers with an item, you make the item record visible to users who have been given permission to access the customer’s data.
From the List tab of the Item Master (SP) application, select the service item that you want to associate customers with.
On the Item tab, click Show/Manage Customers next to the Customer field.
In the Add/Modify Customer Associations window, click Select Customers.
Select one or more customers from the list and click OK.
Click OK to save your changes and return to the Item tab.